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Discussion Starter · #1 ·
Anybody had one made to match the engine characteristics with a 160 kit fitted ?
 

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Do the manufacturers not reccomend a specific exhaust? You could try measuring up various exhausts, then using the spanny chamber formulae to get an indication of which is best, but you'd still be down to trial and error for the best part.

To be honest, i don't think many people will have bothered with a custom exhaust. You could try Stan Stephens to see which exhaust they reccomend. Give the professional tuners a ring, they'll be most likely to have an idea which is the best exhaust.

Jack
 

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Does not know Everything !
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Discussion Starter · #3 ·
I thought i would have to go to the exhaust manufacturer and get a special built, i didnt think of asking the tuners ?!?
 

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2 Strokes And I'm Happy
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might be woth giving dave swarbrick, mick abbey or peter gibson a tinkle as they will all build exhausts for ya.
 

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macdizzy

read above, get hold of programs, measure polini kit, decide on desired power characteristics, make pipe.

Or buy A. Graham Bell's book "two-stroke performance tuning" as it has the formulars.
I was going to suggest using the formulae, but there's still a bit of guesswork that's needed afterwards. Im not sure what it would cost either, could be cheap, could stab you in the wallet.
 

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Discussion Starter · #9 ·
Any more info on that odd sounding part Markus ?
 

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might be woth giving dave swarbrick, mick abbey or peter gibson a tinkle as they will all build exhausts for ya.
swarbricks are still going,i belive that mick abbey has retired(possibly due to ill health) and pete gibson retired at least a couple of years ago,he has passed the gibson name and business to tony and derren at stinkwheels in essex
 

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Discussion Starter · #12 ·
I prefer to take pride in something i have built with my own hands, thanks all the same.
 

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i built a few pipes in the past
its realy not as easy as it looks !!!!! the book by bell has all the stuff yer need to know it says build em strait but thats when it gets nasty as yer have to cut n shut to fitt on the bike n then the formular gets messed with even with much messuring n messin it was dam hard to get just what was wanted
best bet is co called PM tuining i sent em all port timings n what was wanted n they used to knock up pipe in under a week that worked great but it was not cheep
 

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2 Strokes And I'm Happy
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swarbricks are still going,i belive that mick abbey has retired(possibly due to ill health) and pete gibson retired at least a couple of years ago,he has passed the gibson name and business to tony and derren at stinkwheels in essex
yeah swarbrick is still going, werent 100% sure on mick abbey, knew pete gibson was retired but if you search for him on google or something it will bring you to the people who he passed the business onto.
 

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Thanks everybody !

Just watched a couple of the Lufo videos of the RD500 (its omfg yummy) and there ragging the sh*t out of it from new, dont seem to be running it in at all ?

Fair play it looks stoopid fast and revs right out. 'kin ell.
 

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A. Graham Bell's book "two-stroke performance tuning" as it has the formulars.


When using the formulas above for designing or calculating what parameters the pipe to buy should have, the first step is to calculate D1. When you calculate D1 with the D1 formula above, remember that the number is in sq-in and must be converted to the diameter of the header pipe. Do this by dividing your calculation by Pi and then taking the square root. This will give you the radius of the header. Just multiply it by 2 to get the diameter. What you are doing is working the formula for the area of a circle backwards (Area of a circle = Pi r^2). From this point on, no other conversion should be necessary unless you use metric (Multiply numerator of LT formula by 83.3 and use 518.16 m/s for VS to get mm instead of inches) instead of English..... SNIP .....Now comes the fun part! We get to go to the track again, unless of course we have our very own dyno. Not! So we have set the pipe up so that we have an optimum length. Well take it off! That's right, take it off. First we want to get the right prop, right fuel and right needle before we even mess with that pipe. You see this is where the "What a pipe can't do?" comes in. A pipe cannot make up for poor engine setups and crappy gear ratios. A pipe also cannot make up for bad engine timing and some engines are timed so poorly that no pipe will increase performance.

Ok, we make a few (2-3) passes without the pipe. We have the right gear ratio, the right needle setting and this is the fuel we are going to be racing with. Put the pipe back on richen the needle a little and make a run. We pay close attention to what the engine is doing. If the engine turns slower, something is wrong. If the mixture is correct the pipe is too long. Shorten it by 1/8" at a time until the revs start to rise (this can be done at the exhaust coupler). If the pipe is too short the motor will run harshly and the needle setting will be unstable and critical. Add 1/8" to the length at a time (again, at the coupler). When the pipe is at the proper length you will experience the thrill of a lifetime. You will hear the engine and pipe become one in resonance.
Coupled with... http://www.prestwich.ndirect.co.uk/tunedpipetheory2.htm

If you wanna get really flash you could modify the airbox to match the new resonance... but the formulae for it all will give you a severe headache...
 

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Discussion Starter · #18 ·
Theres a lot of wide variances in the given ranges there Marci, D1 is 10 -150 % of so and so. Not exactly precise ?
 

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As helpful that is, in metric it would be pie.
 

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2 Strokes And I'm Happy
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at the end of the day get someone who knows what there doin to build you one, you will f*ck it up if you do it yourself.
 
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